1. Field of the Invention
This invention relates to methods and apparatuses for accessing and modifying intervertebral disc tissue and more particularly to accessing and modifying intervertebral disc tissue using percutaneous techniques that avoid major surgical intervention.
2. Description of Related Art
Intervertebral disc abnormalities have a high incidence in the population and may result in pain and discomfort if they impinge on or irritate nerves. Disc abnormalities may be the result of trauma, repetitive use, metabolic disorders and the aging process and include such disorders but are not limited to degenerative discs (i) localized tears or fissures in the annulus fibrosus, (ii) localized disc herniations with contained or escaped extrusions, and (iii) chronic, circumferential bulging disc.
Disc fissures occur rather easily after structural degeneration (a part of the aging process that may be accelerated by trauma) of fibrous components of the annulus fibrosus. Sneezing, bending or just attrition can tear these degenerated annulus fibers, creating a fissure. The fissure may or may not be accompanied by extrusion of nucleus pulposus material into or beyond the annulus fibrosus. The fissure itself may be the sole morphological change, above and beyond generalized degenerative changes in the connective tissue of the disc. Even if there is no visible extrusion, biochernicals within the disc may still irritate surrounding structures. Disc fissures can be debilitatingly painful. Initial treatment is symptomatic, including bed rest, pain killers and muscle relaxants. More recently, spinal fusion with cages have been performed when conservative treatment did not relieve the pain. The fissure may also be associated with a herniation of that portion of the annulus.
With a contained disc herniation, there are no free nucleus fragments in the spinal canal. Nevertheless, even a contained disc herniation is problematic because the outward protrusion can press on the spinal nerves or irritate other structures. In addition to nerve root compression, escaped nucleus pulposus contents may chemically irritate neural structures. Current treatment methods include reduction of pressure on the annulus by removing some of the interior nucleus pulposus material by percutaneous nuclectomy. However, complications include disc space infection, nerve root injury, hematoma formation, instability of the adjacent vertebrae and collapse of the disc from decrease in height.
Another disc problem occurs when the disc bulges outward circumferentially in all directions and not just in one location. Over time, the disc weakens and takes on a xe2x80x9crollxe2x80x9d shape or circumferential bulge. Mechanical stiffness of the joint is reduced and the joint may become unstable. One vertebra may settle on top of another. This problem continues as the body ages and accounts for shortened stature in old age. With the increasing life expectancy of the population, such degenerative disc disease and impairment of nerve function are becoming major public health problems. As the disc xe2x80x9crollxe2x80x9d extends beyond the normal circumference, the disc height may be compromised, foramina with nerve roots are compressed. In addition, osteophytes may form on the outer surface of the disc roll and further encroach on the spinal canal and foramina through which nerves pass. The condition is called lumbar spondylosis.
It has been thought that such disc degeneration creates segmental instability which disturbs sensitive structures which in turn register pain. Traditional, conservative methods of treatment include bed rest, pain medication, physical therapy or steroid injection. Upon failure of conservative therapy, spinal pain (assumed to be due to instability) has been treated by spinal fusion, with or without instrumentation, which causes the vertebrae above and below the disc to grow solidly together and form a single, solid piece of bone. The procedure is carried out with or without discectomy. Other treatment include discectomy alone or disc decompression with or without fusion. Nuclectomy can be performed by removing some of the nucleus to reduce pressure on the annulus. However, complications include disc space infection, nerve root injury, hematoma formation, and instability of adjacent vertebrae.
These interventions have been problematic in that alleviation of back pain is unpredictable even if surgery appears successful. In attempts to overcome these difficulties, new fixation devices have been introduced to the market, including but not limited to pedicle screws and interbody fusion cages. Although pedicle screws provide a high fusion success rate, there is still no direct correlation between fusion success and patient improvement in function and pain. Studies on fusion have demonstrated success rate of between 50% and 67% for pain improvement, and a significant number of patients have more pain postoperatively. Therefore, different methods of helping patients with degenerative disc problems need to be explored.
One of the challenges associated with treating intervertebral discs is accessing them via percutaneous methods. To appreciate the difficulty presented, the anatomical structure of the spine and an intervertebral disc is illustrated and described below.
FIGS. 1A and 1B illustrate a cross-sectional anatomical view of a vertebra and associated disc and a lateral view of a portion of a lumbar and thoracic spine, respectively. Structures of a typical cervical vertebra (superior aspect) are shown in FIG. 1A: 104xe2x80x94lamina; 106xe2x80x94spinal cord; 108xe2x80x94dorsal root of spinal nerve; 114xe2x80x94ventral root of spinal nerve; 115xe2x80x94posterior longitudinal ligament; 118xe2x80x94intervertebral disc; 120xe2x80x94nucleus pulposus; 122xe2x80x94annulus fibrosus; 124xe2x80x94anterior longitudinal ligament; 126xe2x80x94vertebral body; 128xe2x80x94pedicle; 130xe2x80x94vertebral artery; 132xe2x80x94vertebral veins; 134xe2x80x94superior articular facet; 136xe2x80x94posterior lateral portion of the annulus; 138xe2x80x94posterior medial portion of the annulus; and 142xe2x80x94spinous process. In FIG. 1A, one side of the intervertebral disc 118 is not shown so that the anterior vertebral body 126 can be seen.
FIG. 1B is a lateral aspect of the lower portion of a typical spinal column showing the entire lumbar region and part of the thoracic region and displaying the following structures: 162xe2x80x94intervertebral disc; 142xe2x80x94spinous process; 168xe2x80x94inferior articular process; 170xe2x80x94inferior vertebral notch; 174xe2x80x94superior articular process; 176xe2x80x94lumbar curvature; and 180xe2x80x94sacrum.
The presence of the spinal cord and the posterior portion of the vertebral body, including the spinous process, and superior and inferior articular processes, prohibit introduction of a needle or trocar from a directly posterior position. This is important because the posterior disc wall is the site of symptomatic annulus tears and disc protrusions/extrusions that compress or irritate spinal nerves for most degenerative disc syndromes.
FIG. 1C provides a posterior-lateral anatomical view of two lumbar vertebrae and illustration of the triangular working zone. The inferior articular process 168, along with the pedicle 128 and the lumbar spinal nerve 110, form a small xe2x80x9ctriangularxe2x80x9d window through which introduction of an instrument can be achieved from the posterior lateral approach. FIG. 1D illustrates an instrument (an introducer 169) introduced into an intervertebral disc by the posterior lateral approach.
FIG. 1E illustrates the anatomy of an intervertebral disc in greater detail and shows an introducer 169 inserted into the disc. Structures of the disc are identified and described by these anatomical designations: the posterior lateral inner annulus 136, posterior medial inner annulus 138, annulus fibrosus 122/nucleus pulposus 120 interface, the annulus/dural interface 146, annulus/posterior longitudinal ligament interface 148, anterior lateral inner annulus 150, and the anterior medial inner annulus 152.
The annulus fibrosus 122 is comprised primarily of tough fibrous material, while the nucleus pulposus 120 is comprised primarily of an amorphous colloidal gel. There is a transition zone between the annulus fibrosus 122 and the nucleus pulposus 120 made of both fibrous-like material and amorphous colloidal gel. The border between the annulus fibrosus 122 and the nucleus pulposus 120 becomes more difficult to distinguish as a patient ages, due to degenerative changes. This process may begin as early as 30 years of age. For purposes of this specification, the inner wall of the annulus fibrosus can include the young wall comprised primarily of fibrous material as well as the transition zone which includes both fibrous material and amorphous colloidal gels (hereafter collectively referred to as the xe2x80x9cinner wall of the annulus fibrosusxe2x80x9d). Functionally, the location at which there is an increase in resistance to probe penetration and which is sufficient to cause bending of the distal portion of the probe into a radius less than that of the internal wall 22 of the annulus fibrosus is considered to be the xe2x80x9cinner wall of the annulus fibrosusxe2x80x9d.
As with any medical instrument and method, not all patients can be treated, especially when their disease or injury is too severe. There is a medical gradation of degenerative disc disease (stages 1-5). See, for example, Adams et al., xe2x80x9cThe Stages of Disc Degeneration as Revealed by Discograms,xe2x80x9d J. Bone and Joint Surgery, 68, 36-41 (1986). As these grades are commonly understood, the methods of instrument navigation described herein would probably not be able to distinguish between the nucleus and the annulus in degenerative disease of grade 5. In any case, most treatment is expected to be performed in discs in stages 3 and 4, as stages 1 and 2 are asymptomatic in most patients, and stage 5 may require disc removal and fusion.
It is well known to those skilled in the art that percutaneous access to the disc is achieved by placing an introducer into the disc from this posterior lateral approach, but the triangular window does not allow much room to maneuver. Once the introducer pierces the tough annulus fibrosus, the introducer is fixed at two points along its length and has very little freedom of movement. Thus, with the exception of devices such as those described in U.S. Pat. Nos. 6,135,999; 6,126,682; 6,122,549; 6,099,514; 6,095,149; 6,073,051; 6,007,570; 5,980,504 (which are each incorporated herein by reference), the posterior lateral approach has only allowed access to small central and anterior portions of the nucleus pulposus.
The present invention provides devices and methods which are designed to more efficiently access and treat the interior of intervertebral discs by the posterior lateral approach.
The present invention relates to various embodiments of intervertebral disc devices and their methods of use.
According to one embodiment, the intervertebral disc device comprises a distal probe sized to be extended from a distal end of an introducer that is percutaneously delivered into an interior of an intervertebral disc, a distal section of the probe comprising a flexible neck which tapers in a proximal to distal direction, and a distal tip which is larger in cross sectional diameter than the flexible neck adjacent the distal tip, the flexible neck and distal tip serving to prevent the probe distal end from piercing an internal wall of the intervertebral disc; and a proximal handle for externally guiding the probe within an intervertebral disc.
The flexible neck may optionally be designed such that it is not predisposed to bending in any direction relative to a longitudinal axis of the probe. Alternatively, the flexible neck may be designed to be predisposed to bending along a single plane relative to a longitudinal axis of the probe. Alternatively, the flexible neck may be designed to be predisposed to bending in opposing directions along a single plane relative to a longitudinal axis of the probe. Alternatively, the flexible neck may be designed to be predisposed to bending in at least two different directions along at least two different planes relative to a longitudinal axis of the probe.
According to this embodiment, the flexible neck may optionally have a round cross section. Alternatively, or in addition, the flexible neck may optionally have at least one flat surface extending along a longitudinal axis of the neck. In one variation, the flexible neck has two flat surfaces extending along a longitudinal axis of the neck on opposing sides of the neck.
Also according to this embodiment, the neck may optionally be formed of a flexible coil.
According to this embodiment, the distal tip may optionally have a larger cross sectional diameter than a largest cross sectional diameter of the flexible neck. The distal tip may be symmetrical or asymmetrical. In certain variations, the distal tip is dome shaped or has a flat surface perpendicular to a longitudinal axis of the probe.
The distal tip may be attached to the neck of the probe by a variety of mechanisms including, for example, a spring or a pivot mechanism such as a ball and socket mechanism.
In one preferred variation, the flexibility of the neck of the probe is designed such that it causes the probe to bend and the distal tip to trail behind a portion of the probe as the probe is advanced through tissue within an intervertebral disc. The shape of the distal tip may also contribute to the distal tip trailing behind a portion of the probe.
In another embodiment, an intervertebral disc device is provided comprising: a distal probe sized to be extended from a distal end of an introducer that is percutaneously delivered into an interior of an intervertebral disc, a distal section of the probe comprising an active electrode and a return electrode which are each spirally wrapped around the probe such that there are multiple alternating bands of the same active and return electrodes positioned longitudinally along the length of the distal section of the probe, the active and return electrodes being adapted to deliver bipolar electromagnetic energy to tissue within the intervertebral disc; and a proximal handle for externally guiding the probe within an intervertebral disc.
According to this embodiment, the distal section of the probe may be predisposed to forming a loop.
In another embodiment, an intervertebral disc device is provided comprising: a distal probe sized to be extended from a distal end of an introducer that is percutaneously delivered into an interior of an intervertebral disc, a distal section of the probe being predisposed to forming a loop when extended from the distal end of the introducer, the looping portion of the probe comprising an active electrode and a return electrode which are positioned on the probe such that the active and return electrodes are on opposing sides of the probe loop; and a proximal handle for externally guiding the probe within an intervertebral disc.
In yet another embodiment, an intervertebral disc device is provided comprising: a distal probe sized to be extended from a distal end of an introducer that is percutaneously delivered into an interior of an intervertebral disc, a distal section of the probe comprising separate active and return electrode elements which are predisposed to bending away from each other when extended from the distal end of the introducer; and a proximal handle for externally guiding the probe within an intervertebral disc.
In another embodiment, an intervertebral disc device is provided comprising: a distal sheath sized to be extended from a distal end of an introducer that is percutaneously delivered into an interior of an intervertebral disc, a distal section of the sheath being predisposed to adopting a bent configuration when extended from the introducer; a probe adapted to be extended from a distal end of the sheath, the bent section of the sheath causing the probe to adopt a same bent configuration; and a proximal handle for externally guiding the probe within an intervertebral disc.
In another embodiment, an intervertebral disc device is provided comprising: a distal sheath sized to be extended from a distal end of an introducer that is percutaneously delivered into an interior of an intervertebral disc, a distal section of the sheath being predisposed to adopting a bent configuration when extended from the introducer; a guide wire adapted to be extended from a distal end of the sheath, the bent section of the sheath causing the guide wire to adopt a same bent configuration; a probe adapted to be extended from a distal end of the sheath over the guide wire, the bent section of the sheath causing the probe to adopt a same bent configuration; and a proximal handle for externally guiding the probe within an intervertebral disc.
According to one variation of this embodiment, a distal section of the probe comprises an active electrode and a return electrode which are each spirally wrapped around the probe such that there are multiple alternating bands of the same active and return electrodes positioned longitudinally along the length of the distal section of the probe, the active and return electrodes being adapted to deliver bipolar electromagnetic energy to tissue within the intervertebral disc. Optionally, the distal section of the probe may be predisposed to forming a loop. When the distal section of the probe is predisposed to forming a loop when extended from the distal end of the introducer, the looping portion of the probe may comprise an active electrode and a return electrode which are positioned on the probe such that the active and return electrodes are on opposing sides of the probe loop.
According to another variation of this embodiment, a distal section of the probe comprises separate active and return electrode elements which are predisposed to bending away from each other when extended from the distal end of the introducer.
In another embodiment, an intervertebral disc device is provided comprising: a probe capable of being extended from a distal end of an introducer that is percutaneously delivered into an interior of an intervertebral disc, the probe forming a loop when extended from the distal end of the introducer, the loop having first and second proximal ends external to the introducer which are brought together adjacent the introducer distal end to form the loop by the proximal ends being either attached to or entering the distal end of the introducer; and a proximal handle for externally causing the probe to be extended from the distal end of the introducer and externally guiding the probe within an intervertebral disc.
According to this embodiment, the device may optionally further include an introducer, the first proximal end of the probe being attached to the introducer adjacent a distal end of the introducer, the second proximal end of the probe being extendable from the introducer distal end to form the loop. According to this variation, the first proximal end of the probe may optionally be attached to the introducer adjacent the distal end of the introducer by a guide wire lead. Alternatively, the first and second proximal ends of the probe may each be separately extendable from the introducer distal end to form the loop. When the first and second proximal ends of the probe are each separately extendable from the introducer distal end to form the loop, the first and second proximal ends of the probe may have different cross sectional geometries. According to this variation, the different cross sectional geometries of the first and second proximal ends may be selected such that the cross sectional geometry of the first proximal end is a compliment of the cross sectional geometry of the second proximal end.
In another embodiment, an intervertebral disc device is provided comprising: a guide wire capable of being extended from a distal end of an introducer that is percutaneously delivered into an interior of an intervertebral disc, the guide wire forming a loop when extended from the distal end of the introducer, the loop having first and second proximal ends external to the introducer which are brought together adjacent the introducer distal end to form the loop by the proximal ends being either attached to or entering the distal end of the introducer; a probe capable of being extended over the guide wire from the distal end of the introducer; and a proximal handle for externally causing the guide wire and probe to be extended from the distal end of the introducer and externally guiding the guide wire and probe within an intervertebral disc.
In one variation of this embodiment, the device further includes an introducer, the first proximal end of the guide wire being attached to the introducer adjacent a distal end of the introducer, the second proximal end of the guide wire being extendable from the introducer distal end to form the loop. In another variation, the first and second proximal ends of the guide wire are each separately extendable from the introducer distal end to form the loop.
In another embodiment, an intervertebral disc device is provided comprising: guide wire capable of being extended from a distal end of an introducer that is percutaneously delivered into an interior of an intervertebral disc, a distal section of the guide wire being predisposed to forming a loop when extended from the distal end of the introducer, the looped distal section of the guide wire serving to localize the looped distal section within the intervertebral disc; a probe capable of being extended over the guide wire from the distal end of the introducer, the probe and guide wire being extendable in combination such that position of the looped distal section of the guide wire is not changed; and a proximal handle for externally causing the guide wire and probe to be extended from the distal end of the introducer and externally guiding the guide wire and probe within an intervertebral disc.
According to any of the above embodiments, the device may further include flexible tubing operably interconnecting the proximal handle with the distal probe. The probe and/or guide wire may optionally extend within the flexible tubing to the handle.
Also according to any of the above embodiments, the device may further include a connector system which enables an introducer to be removeably attached to the connector system, the probe being positionable within the introducer for delivery within the intervertebral disc with the assistance of the introducer.
According to any of the above embodiments, the device may further include a probe or guide wire with a mechanism for securing the probe or guide wire within the selected section of the intervertebral disc. The mechanism may be a curved portion adjacent the distal end capable of anchoring the probe or guide wire into tissue. The curved distal portion preferably forms a distal end of the probe or guide wire. The curved distal portion is optionally retractable and optionally divides into multiple separate curved portions, such as to form a treble hook.
Also according to any of the above embodiments, the probe may further include a functional element which performs a function. A wide variety of functions may be performed by the functional element including, but not limited to, transmitting energy to tissue within an intervertebral disc, delivering material to within an intervertebral disc, and removing material within an intervertebral disc.
When the function element transmits energy, the probe may further include an electromagnetic energy device capable of supplying energy within the intervertebral disc. The electromagnetic energy device may be capable of delivering energy selected from group consisting of coherent and incoherent light and radiofrequency (RF), microwave, and ultrasound waves. When delivering RF energy, the electromagnetic energy device comprises electrodes adapted to deliver RF energy. The RF electrodes may adopt a monopolar or bipolar configuration. The electromagnetic energy device may also comprise a resistive heating mechanism.
Also according to any of the above embodiments, the handle may further comprise a probe control element for controlling the movement of the probe adjacent a distal end of the device. The device may also comprise a guide wire control element for controlling the movement of the guide wire adjacent a distal end of the device.
Methods are also provided for employing the various devices of the present invention to treat an interior of an intervertebral disc.
In one embodiment, the method comprises inserting an introducer through a skin of a person such that the distal end of the introducer travels within the person via a posterior lateral approach to an intervertebral disc such that a distal end of the introducer is positioned in or adjacent an intervertebral disc; extending a probe from a distal end of the introducer such that the probe is positioned within the intervertebral disc; and treating tissue within the interior of the intervertebral disc using the probe. The probe that is extended from the introducer may have any of the various probe designs described herein.
In another embodiment, the method comprises inserting an introducer through a skin of a person such that the distal end of the introducer travels within the person via a posterior lateral approach to an intervertebral disc such that a distal end of the introducer is positioned in or adjacent an intervertebral disc; extending a guide wire from a distal end of the introducer such that the guide wire is positioned within the intervertebral disc; extending a probe over the guide wire, and treating tissue within the interior of the intervertebral disc using the probe. The guide wire and probe that are extended from the introducer may have any of the various guide wire and probe designs described herein.
In another embodiment of the invention, a method for delivering a probe is provided. The method comprises extending a guide wire into an intervertebral disc such that the guide wire is positioned within the intervertebral disc adjacent an inner wall of the disc; attaching a distal portion of the guide wire to the inner wall; and extending a probe over the guide wire. The guide wire and probe that are extended may have any of the various guide wire and probe designs described herein.
According to this embodiment, the step of attaching the distal portion of the guide wire may be accomplished by inserting a portion of the guide wire into the tissue of the inner wall of an intervertebral disc such that the distal portion is held in place and retained by the tissue of the inner wall of the disc. In this regard, a variety of attachment mechanisms may be employed. For example, the step of attaching the distal portion of the guide wire may be by hooking the attachment mechanism into the tissue of the inner wall such that the distal portion is held in place and retained by the tissue of the inner wall of the disc. The attachment mechanism may be a curved distal portion of the guide wire.
All of the above embodiments involving attaching the guide wire to the inner wall of an intervertebral disc may be adapted where the probe instead of the guide wire comprises an attachment mechanism for attaching the probe to the inner wall.